Diagnostic performance of [(18)F]fluorodeoxyglucose positron emission tomography-computed tomography in cyst infection in patients with autosomal dominant polycystic kidney disease.

Cyst infection is a common complication of autosomal dominant polycystic kidney disease (ADPKD). Diagnosis is challenging with standard imaging techniques. We aimed to evaluate the diagnostic performance of [(18)F]fluorodeoxyglucose positron emission tomography-computed tomography (18-FDG PET-CT) for the diagnosis of cyst infections among ADPKD patients, in comparison with computed tomography (CT) and magnetic resonance imaging (MRI). All APKD patients who underwent 18-FDG PET-CT for suspected cyst infection between 2006 and 2013 in a French teaching hospital were included. Diagnosis of cyst infection was retained a posteriori on an index of clinical suspicion. 18-FDG PET-CT findings were was considered to be positive in cases of cyst wall hypermetabolism. CT or MRI findings were were considered to be positive in cases of cyst wall thickening (and enhancement if contrast medium was injected) and infiltration of the adjacent fat. A control group of ADPKD patients with 18-FDG PET-CT performed for other reasons was included. Thirty-two 18-FDG PET-CT scans were performed in 24 ADPKD patients with suspected cyst infection. A diagnosis of cyst infection was retained in 18 of 32 cases: 14 with positive 18-FDG PET-CT findings, and four false negatives. There were no false positives and no hypermetabolism of cyst walls in nine ADPKD control patients. 18-FDG PET-CT had a sensitivity of 77%, a specificity of 100%, and a negative predictive value of 77%. 18-FDG PET-CT allowed a differential diagnosis in three patients. In contrast, CT had a sensitivity of 7% and a negative predictive value of 35% (p <0.001 vs. 18-FDG PET-CT). Only eight MRI scans were performed. The diagnostic performance of 18-FDG PET-CT is superior to that of CT in cyst infections, for comparable radiation doses and with no injection of nephrotoxic contrast medium, in ADPKD patients.

(18)F-FDG uptake at initial staging of the adrenocortical cancers: a diagnostic tool but not of prognostic value.

BACKGROUND: Adrenocortical carcinoma (ACC) is a rare cancer for which little level evidence exists to guide management. (18)F-FDG PET ((18)F-fluorodeoxyglucose positron emission tomography) is an increasingly used diagnostic tool in patients with suspicious or indeterminate adrenal tumors. In some other solid tumors, (18)F-FDG PET may offer prognostic information that can guide optimal patient treatment. The aim of the present study was to evaluate whether preoperative (18)F-FDG PET based on SUVs assessments has a prognostic value in ACC patients. METHODS: A retrospective analysis was performed in patients who underwent (18)F-FDG PET/CT for the evaluation of ACC. Inclusion criteria were an unequivocal diagnosis of ACC; all data from primary diagnosis available; (18)F-FDG PET/CT performed prior to surgery or other treatment of the primary tumor; a minimum of 6-months follow-up for surviving patients. All (18)F-FDG PET/CT procedures were reinterpreted in a blind fashion. RESULTS: Thirty-seven patients (23 without metastasis [M0], 14 with metastasis [M1]) fulfilled the study criteria. Median uptake values were tumor standardized uptake values (SUV)(max) = 11 (range: 3-56) and a tumor/liver SUV(max) ratio = 4.2 (range: 1.3-15). Median follow-up was 20 months. Although classic risk factors (tumoral stage, Weiss score) were associated with poor outcome, there was no correlation between primary tumor FDG uptake with overall survival (OS) and disease free survival (DFS) in M0 patients and with overall survival in M1 patients. (18)F-FDG uptake correlated inconsistently with sinister histological features, such as atypical mitoses or necrosis. CONCLUSIONS: At initial staging, primary tumor FDG uptake in ACC patients does not correlate with OS and DFS at 2 years. Patient prognosis and treatment strategy should not be based on uptake values.

Radioiodine thyroid ablation in graves' hyperthyroidism: merits and pitfalls.

Ablative approaches using radioiodine are increasingly proposed for the treatment of Graves' disease (GD) but their ophthalmologic and biological autoimmune responses remain controversial and data concerning clinical and biochemical outcomes are limited. The aim of this study was to evaluate thyroid function, TSH-receptor antibodies (TRAb) and Graves' ophthalmopathy (GO) occurrence after radioiodine thyroid ablation in GD. We reviewed 162 patients treated for GD by iodine-131 ((131)I) with doses ranging from 370 to 740 MBq, adjusted to thyroid uptake and sex, over a 6-year period in a tertiary referral center. Collected data were compared for outcomes, including effectiveness of radioiodine therapy (RIT) as primary endpoint, evolution of TRAb, and occurrence of GO as secondary endpoints. The success rate was 88.3% within the first 6 months after the treatment. The RIT failure was increased in the presence of goiter (adjusted odds ratio = 4.1, 95% confidence interval 1.4-12.0, P = 0.010). The TRAb values regressed with time (r = -0.147; P = 0.042) and patients with a favorable outcome had a lower TRAb value (6.5 ± 16.4 U/L) than those with treatment failure (23.7 ± 24.2 U/L, P < 0.001). At the final status, 48.1% of patients achieved normalization of serum TRAb. GO occurred for the first time in 5 patients (3.7%) who were successfully cured for hyperthyroidism but developed early and prolonged period of hypothyroidism in the context of antithyroid drugs (ATD) intolerance (P = 0.003) and high TRAb level (P = 0.012). On the basis the results of this study we conclude that ablative RIT is effective in eradicating Graves' hyperthyroidism but may be accompanied by GO occurrence, particularly in patients with early hypothyroidism and high pretreatment TRAb and/or ATD intolerance. In these patients, we recommend an early introduction of LT4 to reduce the duration and the degree of the radioiodine-induced hypothyroidism.

Limited value of 18F-F-DOPA PET to localize pancreatic insulin-secreting tumors in adults with hyperinsulinemic hypoglycemia.

CONTEXT: Fluorine-18-L-dihydroxyphenylalanine positron emission tomography (18F-FDOPA PET) imaging is increasingly used in the workup of neuroendocrine tumors. It has been shown to be an accurate tool in the diagnosis of congenital hyperinsulinism, but limited information is available on its value in adult disease. OBJECTIVE, PATIENTS, AND DESIGN: The objective of this study was to review our experience with 18F-FDOPA PET imaging in six consecutive patients with hyperinsulinemic hypoglycemia (HH) (four solitary insulinomas, one diffuse beta-cell hyperplasia, one malignant insulinoma). 18F-FDOPA uptake was also evaluated in 37 patients (43 procedures) without HH or other pancreatic neuroendocrine tumors, which acted as a control group. RESULTS: Using visual analysis, 18F-FDOPA-PET proved positive in only one case (a multiple endocrine neoplasia type 1 related insulinoma). In diffuse beta-cell hyperplasia, the pancreatic uptake was similar to controls. In the patient with liver metastases, the extent of disease was underestimated. The pancreatic uptake was not statistically different between controls and hyperinsulinemic patients. The main limitation for identifying insulinomas or beta-cell hyperplasia in adults appears to be to the 18F-FDOPA uptake and retention in the whole pancreas. This drawback is potentially circumvented in focal hyperplasia in newborns due to a lower aromatic amino acid decarboxylase expression in the extralesional pancreatic parenchyma. CONCLUSIONS: 18F-FDOPA PET is of limited value in localizing pancreatic insulin secreting tumors in adult HH. Our results contrast with the referential study and require further analysis.

Management of cervical lymph node recurrence of melanoma of the head and neck.

OBJECTIVES: To compare the diagnostic accuracy between Positron emission tomography using 2-[fluorine-18] fluoro-2-deoxy-D-glucose (FDG-PET scan) and conventional work-up such as ultrasound (US) and/or Computed tomography (CT) in the detection of cervical lymph node recurrences of melanoma of the head and neck after initial cervical lymph node surgery. METHODS: A retrospective review was performed on patients who presented with clinical and/or radiological suspicion of isolated cervical lymph node recurrence after lymph node surgery from April 2004 to January 2007. All patients underwent CT and/or US of the neck, and FDG-PET scan before salvage neck dissection. None of included patients had clinical or radiological detectable distant metastases at the time of the lymph node dissection. Performances of conventional imaging and FDG-PET scan in detection of lymph node recurrence were calculated and compared by using the histopathological results of lymphadenectomy as gold standard with Fischer's exact test. RESULTS: Of the twelve cases in included in the study (9 patients, 3 of them had 2 consecutive lymph node redissection for a second lymph node recurrence), melanoma recurrence was found in 10 cases (83%). Sensitivity, specificity, positive predictive value and negative predictive values were 78.6%, 40%, 78.6%, and 40% respectively for conventional imaging and 85.7%, 40%, 80% and 50% for FDG-PET scan. No statistically significant difference was found between the 2 methods. CONCLUSION: This is the first study that compares the diagnostic accuracy between FDG-PET scan and conventional imaging in the detection of cervical lymph node recurrence of melanoma of the head and neck. Our results showed that FDG-PET scan is actually not better than conventional imaging to detect these cervical lymphatic recurrences.

Does 18F-FDG PET/CT add diagnostic accuracy in incidentally identified non-secreting adrenal tumours?

PURPOSE: The widespread use of high-resolution cross-sectional imaging such as computed tomography (CT) and magnetic resonance imaging (MRI) for the investigation of the abdomen is associated with an increasing detection of incidental adrenal masses. We evaluated the ability of (18)F-fluorodeoxyglucose positron emission tomography to distinguish benign from malignant adrenal masses when CT or MRI results had been inconclusive. METHODS: We included only patients with no evidence of hormonal hypersecretion and no personal history of cancer or in whom previously diagnosed cancer was in prolonged remission. PET/CT scans were acquired after 90 min (mean, range 60-140 min) after FDG injection. The visual interpretation, maximum standardised uptake values (SUVmax) and adrenal compared to liver uptake ratio were correlated with the final histological diagnosis or clinico-radiological follow-up when surgery had not been performed. RESULTS: Thirty-seven patients with 41 adrenal masses were prospectively evaluated. The final diagnosis was 12 malignant, 17 benign tumours, and 12 tumours classified as benign on follow-up. The visual interpretation was more accurate than SUVmax alone, tumour diameter or unenhanced density, with a sensitivity of 100% (12/12), a specificity of 86% (25/29) and a negative predictive value of 100% (25/25). The use of 1.8 as the threshold for tumour/liver SUVmax ratio, retrospectively established, demonstrated 100% sensitivity and specificity. CONCLUSION: FDG PET/CT accurately characterises adrenal tumours, with an excellent sensitivity and negative predictive values. Thus, a negative PET may predict a benign tumour that would potentially prevent the need for surgery of adrenal tumours with inconclusive conventional imaging.

The role of 18F-FDOPA and 18F-FDG-PET in the management of malignant and multifocal phaeochromocytomas.

BACKGROUND: (18)F-DOPA has emerged as a promising tool in the localization of chromaffin-tissue-derived tumours. Interestingly, phaeochromocytomas (PHEO) are also FDG avid. AIM AND METHODS: The aim of this study was to retrospectively evaluate the results of (18)F-FDOPA and/or (18)F-FDG-PET in patients with PHEO and paragangliomas (PGLs) and to compare the outcome of this approach with the traditional therapeutic work-up. Nine patients with non-MEN2 related PHEO or PGL were evaluated. At the time of the PET studies, the patients were classified into three groups based on their clinical history, conventional and SPECT imaging. The groups were malignant disease (n = 5, 1 VHL), apparently unique tumour site in patients with previous surgery (n = 1, SDHB) and multifocal tumours (n = 3, 1 VHL, 1 SDHD). (18)F-FDOPA and (18)F-FDG-PET PET/CT were then performed in all patients. RESULTS: PET successfully identified additional tumour sites in five out of five patients with metastatic disease that had not been identified with SPECT + CI. Whilst tumour tracer uptake varied between patients it exhibited a consistently favourable residence time for delayed acquisitions. (18)F-FDOPA uptake (SUVmax) was superior to (18)F-FDG uptake in cases of neck PGL (three patients, four tumours). If only metastatic forms and abdominal PGLs were considered, (18)F-FDG provided additional information in three cases (two metastatic forms, one multifocal disease with SDHD mutation) compared to (18)F-FDOPA. CONCLUSIONS: Our results suggest that tumour staging can be improved by combining (18)F-FDOPA and (18)F-FDG in the preoperative work-up of patients with abdominal and malignant PHEOs. (18)F-FDOPA is also an effective localization tool for neck PGLs. MIBG however, still has a role in these patients as MIBG and FDOPA images did not completely overlap.